Figure 3.

Mechanical characteristics of the sweat‐activated battery (SAB). a,b) Optical images of the SAB as stretched to various rates, including 0, 6%, 32.4%, 49.4%, and 75.2%, and the corresponding voltage outputs, fluctuating between 0.91 and 0.93 V. c) Electrical response of the SAB during repeated cycles (>800) of stretching ≈6% at a constant frequency of 3.6 Hz. d,e) Optical images of the battery bent at different angles from 45° to 180°, and the corresponding electrical responses. f) Optical images of the crash test setup. g) Electrical response of the battery as the five different weights hit it from a constant height of 15 cm, as shown in (f). h) Electrical response of the battery as the 500 g weight continuously hits it 500 times at a constant frequency of ≈0.42 Hz.